So I've sold my sv with just 2 1/2 weeks left to run on my policy but my insurer says they won't switch over to my Daytona because it has no immobiliser.

What can I do to get me through the next two and a bit weeks where by my bike will only be locked in a garage to get the extra year no claims?

Simplest thing to do is nothing.
Just let the policy run to the end date, then when policy ends insure the Daytona through another insurer.
If you can't get cover with any insurer, fit an immobiliser.

Also worth doing a check on confusethemeerkats etc to see what difference the one year additional no claims discount actually makes.
Get quotes for Xyrs NCD and X-1yrs NCD
Chances are it won't be worth bothering about.
I have full no claims and for some bikes it makes no significant difference to the quote with or without the NCD.